26 REPOKT UNITED STATES GEOLOGICAL SUEVEY. 



yond the end of the laceolite and a little above, a series of yellowish 

 limestones which belong to the series passing over the arch of the lac- 

 eolite. From these beds I obtained the following fossils : 



Spirifer Rocky Mountaincnsis. 

 Athyrus stibtUeta. 

 Hemipronites crinistreata. 

 Zaphrentls Stansburyii. 

 Productus. (?) 

 Terebratula. (?) 



The occurrence of the Carboniferous rocks so low down surprises me 

 somewhat, as there can hardly be more than 500 feet interval for the Si- 

 lurian strata, between this and the granite. In Mount Holmes there 

 was apparently a much greater thickness. The thickness cannot well 

 be determined until some approximate idea of the thickness of the in- 

 trusive sheets is obtained. 



At camp, which I found on Panther Creek, far along the east base of 

 the mountains, I observed that the drift contained fossil-bearing Carbon- 

 iferous limestones, many of the species being the same as those enum- 

 erated above. Snow fell during the night to the depth of several inches, 

 and the following day was spent in a successful elk hunt. 



On the morning of the 12th we concluded to send the outfit to the 

 Springs and close the season's work, as it was impossible to continue the 

 topographical work, and geologic examination was by no means satis- 

 factory. I spent the day, however, on the lower ends of the spurs that 

 lie between Panther Creek and Electric Peak, and succeeded in com- 

 pleting, in a general way, the section of the sedimentary strata of this 

 range, as given in Plate XIV. 



From camp on Panther Creek, I passed to the north for about three 

 miles, along the base of the range, and ascended the table-like spur at 

 the first accessible point. The section exposed in the steep clifl's to the 

 west of the place of ascent is as follows: At the base, less than 100 feet 

 of hard rough-surfaced and brecciated limestone that probably overlies 

 the fossiliferous limestones observed a mile or two farther south. Upon 

 these rest the compact, massive, yellowish quartzites which form the 

 main series of cliffs of this part of the range. There are upwards of 300 

 feet of these strata. Above these, and forming the upper part of the 

 ledge, are 20 or 30 feet of laminated limestone and calcareous sand- 

 stones ; these contain some indistinct impressions of fossils — probably a 

 species of lingula — which would indicate the Jurassic age of the strata. 

 Above the brink of the cliffs a steep slope reaches up to the top of th<. 

 mountain. 



The upper surface of this mountain is quite broad and has a slope con- 

 forming with the dip of the strata at an angle of 3° or 4P to the north. 

 Far up the incline, toward the crest of the range, a few fragments of 

 superior strata still remain upon the compact stratum that has so suc- 

 cessfully arrested the progress of erosion. On the north there is an 

 abrupt descent of about 500 feet to the valley of Fawn Creek. Here 

 the compact quartzites are again exposed, but the limestones which 

 occur at the base of the preceding section are beneath the creek bed and 

 do not appear. North of the creek, I ascended a steep terraced slope, 

 to the crest of the first great spur south of Electric Peak. At an eleva- 

 tion of 500 feet I reached an outcrop of coarse gray sandstone, some 30 

 feet of which were exposed. Near the summit of the ridge, at an eleva- 

 tion of 12,000 feet above the creek, some thin seams of limestone appear 

 through the heavy alluvial deposits, in these are great numbers of a 



